What is the connection between clowns and Irish immigrants?

Irrespective of whether you love or hate them, clowns represent a great part of the 20th century entertainment industry, especially for children. But what is the connection between clowns and Irish immigrants?

Bushy red hair, large, red nose and colourful clothes, ‘Clowns’ in other words, used to function as a parody for the poor Irish immigrants in the past!